Paper and method of making same



I May 11, 1943. L. L. DODGE 23 PAPER AND METHOD OF MAKING SAME Filed March 1, 1939 r N I a \2 F Libya L. D0005. L

Patented May H 1943 UNITED STATES PATENT OFFICE 2,319,116 PAPER AND METHOD or MAKING SAME Lloyd L. Dodge, Chicago, Ill., assignor to Rhinelander Paper Company, Rhinelander, Wis., a corporation of Wisconsin 1 Application March 1, 1939, Serial No. 259,151

8 Claims.

This invention relates to the preparation of paper having a high degree of transparency, pliability and moistureprooiness. More specifically the invention relates to the preparation of paper of enhanced transparency and pliability,

that is especially well adapted for use on automatic wrapping and sealing machines.

In my U. S. Patents Nos. 1,992,996, dated March 5, 1935, and 2,099,726, dated November springiness when waxed which precludes their satisfactory use on automatic wrapping machines. Such automatic wrapping machines usually fold portions of the waxed paper on itself and seal the fold around the wrapped article by melting the wax on the sheet.

In my Patent No. 1,992,996 a sheet of partially hydrated chemical pulp, preferably sulphite pulp, is formed into a web, dried and plasticized with from 2% to 10% of a plasticizer such as glycerin, glycols, sugars, deliquescent salts 'or the like. The plasticized sheet is then supercalendered while in a moist condition. The plasticized and supercalendered sheet can then be waxed.

In my Patent No.. 2,099,726 I have described and claimed a method of producing a superior sheet by subjecting the non-greaseproof web, prior to the final waxing operation, to treatment with an aqueous emulsion of wax.

According to the present invention non-greaseproof paper is subjected after supercalendering to a treatment with molten petrolatum or other amorphous, high-melting hydrocarbon, prior to the final waxing operation. While the particular high melting point hydrocarbons that are preferred for use in the practice of the present invention are here referred to as amorphous, they are now known to be micro crystalline waxes. These waxes are produced directly from petroleum by the usual steps of separation customarily practiced in the industry for some years past. The paper, prior to being treated acco ding to this invention, may be plasticized and supercalendered in accordance with the teachings of my patent No.'1,992,996.

.The petrolatum used in the method of this inventlon has a melting point of between 140 and 155 F. Since paraffin waxes seldom have melting points exceeding 138 F., the petrolatum applied to the sheet prior to the final waxing operation'will not bleed through the final wax coatingl- It is, then, an object of this invention to treat paper, with petrolatum or other high-melting amorphous hydrocarbon prior. to waxing the paper.- 1

A further object of the invention is to provide a non-greaseproof waxed paper impregnated with petrolatum. a

A specific object of the invention is to provide a non-greaseproof, transparent, pliable and moisturproof sheet of paper impregnated with petrolatum and provided with an overlying coating of wax.

Another object of the invention is to use a relatively high melting-point petrolatum for treating a sheet of non-'greaseproof paper prior to waxing the sheet.

. Other and further objects of the invention will become apparent to those skilled in the art.

from the'following specific example of the process of preparing paper according to this invention.

The method of this invention (in a preferred form) is illustrated in the drawing'and hereinafter more fully described.

On the drawing:

The figure shown is a diagrammatic side elevational View of apparatus suitable for carrying out the method of my invention, with a part thereof shown'in section.

A chemical pulp, as for example bleached spruce sulphite pulp or other types of bleached or unbleached sulphite. sulphate or soda pulp. may be used as the furnish to form the paper of this invention. The ulp is beaten only sufiiciently to separate and comb out the fibers and to produce a free stock. The beating opera tion is terminated before the hydration of the pulp proceeds sufliciently to produce a greaseproof paper.

A greaseproof paper may be defined as a paper which resists the penetration of spirits of turpenpentine to spread outside of the sand pile at least one-eighth inch. A highly enameled book paper is placed beneath the-paper being tested.

The book paper is examined at intervals until a spot shows on the paper. If the elapsed time for the spot formation on the book paper is over one minute, the paper being tested is classed as a greaseproof paper.

The non-greaseproof paper intended for use in the method of this invention shows almost instantaneous penetration of the turpentine in a test such as above described, and seldom resists penetration of the turpentine for a period.

of time exceeding three to five seconds.

The partially hydrated free furnish is converted into paper, preferably on a Yankee Fourdrinier machine, to form a sheet in which the fibers lie mainly in the direction of travel of the machine- The paper, after being dried on the machine, or during the drying operation, may be treated with 2 /2 to 10% of plasticizers by weight prior to a supercalendering operation, asis more fully disclosed in my Patent No. 1,992,-

996 above referred to. Alternatively, the paper can be treated with a wax emulsion prior to the supercalendering operation as is more fully described in my Patent No. 2,099,726 above referred to. If desired, either the plasticizing treatment, the wax emulsion treatment, or both can be omitted.

The method of my invention may be best understood by reference to the accompanying drawing. The paper-to be treated, which may be in the form of a mill roll I0, is guided by means of rollers II and I2 into contact with the surface of a fountain roll la, the lower portion of which is immersed in a bath Id of molten petrolatum. Said petrolatum is contained within a tank l-5 provided with heating elements l6, such, as steam pipes, for maintaining the petrolatum in a molten condition, preferably at a temperature of from 150 to 175 F. As the fountain roll is revolves, it picks up a film of molten petrolatum, the excess of which is doctored off by means of a roll or rod doctor [1. The film of petrolatum remaining on the foun tain roll is transferred to the underside of the paper web i8.

The amount of petrolatum transferred to the web I8 may further be controlled by a doctor l9, positioned beyond the fountain roll i3, so that the sheet will not take up more petrolatum than it can retain without causing bleeding" after the sheet has been waxed. In general, the amount of petrolatum with which the sheet is impregnated should be between 0.5 and 5.0% by weight of the paper, with a preferred range of between 1.5 and 2.5% by weight. As a typical example, if the basis weight of the paper is 21 lbs. per ream of 500 sheets, each 24" x 36'', lb. of petrolatum per ream of paper gives excellent results. With heavier or lighter weights of paper, the amount of petrolatum left in the sheet will vary accordingly.

After leaving the fountain roll l3, the web l8 passes around a steam heated roll 20 and a second, larger steam heated ro-l 2i, and thence is guided, as by means of guide rolls 22 and 23, to a rewinder comprising a pair of lower driven rolls 24 and 25 mounted upon a suitable standard 26. The treated paper is wound up on the rewinder into a roll 21. Owing to the speed of travel of the paper, which may be in the neighborho'od of 500 feet per minute, the treated paper is still hot, usually in the neighborhood of 150 F; when rewound into the roll 21. Consequently, while the treated paper is in the form of the roll 21, the petrolatumhas an opportunity to become thoroughly and uniformly impregnated throughout the entire body of the roll and about the individual fibers of the paper. It is not necessary to hold the roll 21 for any predetermined period of time before subjecting the petrolatum impregnated paper to a waxing operation, but it may be held for a short period to complete the uniform penetration of the molten petrolatum into the paper web.

After the petrolatum has been thoroughly incorporated into the sheet, the roll is unwound and wet waxed by passing through a molten bath practices.

of parafiin wax in accordance with well known Considerably less wax is picked up by the paper, owing to the presence of the petrolatum in the sheet, so that a substantial saving may be eifected by virtue of the use of the less expertsive petrolatum in place of part of the paraflln wax. Furthermore, only a single waxing step is required, as contrasted with the usual double waxing step commonly employed heretofore.

The petrolatum serves to close up the sheet and impart thereto higher moistureproofness than can be obtained by the use of wax alone. Furthermore, the use of petrolatum gives the sheet greater flexibility and a higher degree of trans- I parency.

a By proper control of the amount of petrolatum introduced into the sheet, by the means hereind of petrolatum.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. In the method of making a waxed nongreaseproof paper of enhanced transparency and pliability from relatively free, partially hydrated stock by successively forming the stock into a paper web having its fibers lying largely in the machine direction, drying, moistening and supercalendering the web, the steps which comprise coating one side of the web with an amorphous petrolatum having a melting point between and F., doctoring off excess petrolatum from the web so as to leave the web impregnated with an amount of said petrolatum insuiilcient to bleed through the wax, winding the petrolatum treated web into a roll while at a temperature above the melting point of the petrolatum to insure the petrolatum being uniformly fiuxed into the web and thereafter applying a coating of parafiin wax to the petrolatum impregnated web.

2. In the method of making waxed nongreaseproof paper of enhanced transparency and pliability from relatively free, only partially hydrated paper stock by forming the stock into a paper web having its fibers lying largely in the machine direction and supercalendering said web, the improvement which comprises coating one side of the web with crude amorphous petrolatum having a melting point of between 140 and 155 F., doctoring off excess petrolatum from the web so that'said web contains from 1.5 to 2.5% by weight of petrolatum, winding the petrolatum treated web into a roll while at a temperature above the melting point of the petrolatum and thereaftercoating the web with paraffin wax.

3. A sheet of paper impregnated with petrolatum and having a paraflin wax coating overlying the petrolatum impregnated sheet, said petrolatum having a melting point higher than that of the wax.

4. Wrapping paper suitable for use on automatic wrapping and sealing machines comprising a sheet formed from free chemical pulp stock, said sheet having the fibers thereof lying mainly in one direction, a high melting-point amorphous petrolatum impregnating said sheet and an outer parafflnwax coating thereover, said petrolatum having a melting point higher'than that of the wax.

5. A waxed, non-greaseproof paper of enhanced transparency, -pliability and moistureproofness comprising a sheet having the fibers thereof lying mainly in one direction and impregnated with amorphous petrolatum and a parafiin wax coating having a lower melting point than the petrolatum covering the sheet, the petrolatum being present in insufflcient amount to bleed through said wax coating.

6. In the method of making a relatively transparent, pliable, moisture-proof sheet of waxed paper from relatively free paper stock by Suecessively forming the stock into a paper web having its fibers lying mainly in the machine direction, drying, moistening, and supercalendering the web, the steps which comprise impregnating the web with molten petrolatum having a. melting point higher than that oi the wax used, regulating the petrolatum content of the web by doctoring the petrolatum so as to leave the web impregnated with an amount of said petrolatum insufficient to bleed throughthe wax, and thereafter applying a coating of paraflin wax to the web and over the petrolatum.

'7. In the method of making awaxed paper of enhanced transparency and pliability from relak tively free paper stock by successively forming the stock into a paper web having its fibers lying mainly in the machine direction,'drying, moistening, and supercalendering the web, the steps which comprise coating one side only of the web with molten petrolatum having a melting point higher than that of the wax used, allowing said petrolatum in an amount between 0.5 and 5% by weight of said web to remain on the web, reeling the petrolatum-treated web into a roll while at a temperature above the melting point of the petrolatum to flux the petrolatum into the web,

thereafter unreeling the web, and passing the web through a molten parafiin wax bath for waxing the web.

8. A sheet of paper impregnated with from 0.5 to 5% by weight of petrolatum, and a paraffin wax coating overlying the impregnated sheet, said paraflin wax having a lower melting point than the petrolatum.

- LLOYD L. DODGE. 

